Conventional speed control in electric power tools is achieved by means of a potentiometer or the like having a variable resistor, such as a thin carbon film, that is disposed on a printed circuit board. The effective resistance of the thin carbon film may be varied, for instance, in response to movement of a trigger actuator, by sliding conductive wipers of the potentiometer upon a surface of the thin carbon film. A variable voltage measured across the variable resistor can then be utilized as an indicator of the movement of the actuator and the basis for controlling the speed of the motor. As the thin carbon film is subjected to repeated sliding movement with the conductive wipers, both the thin carbon film and the conductive wipers may undergo considerable wear and tear which may ultimately result in inaccurate or erratic speed control operation. Also, the thin carbon film tends to be exposed to contaminant particles which not only have a tendency to cause short-circuiting of tracks on the conductive pads, but, may also exacerbate the damage caused by scraping of the conductive wipers along the thin carbon film.